PB2605: EFFICACY AND SAFETY OF MRNA COVID VACCINES IN ITP PATIENTS: A MONOCENTRIC REAL-LIFE STUDY
Authors: Simona D’angelo, Francesca Morelli, Cristina Giubbilei, Vivian Paradiso, Alessandro Vannucchi, Valentina Carrai
Journal: HemaSphere (2023)

Topic: 32. Platelet disorders Background: COVID-19 pandemic has had several implications in hematological patients (pts). Due to the problems that immune thrombocytopenic purpura (ITP) pts may have because of vaccines, different studies have been conducted to evaluate their safety. In one, Visser et al., enrolled 218 ITP pts and only 30(14%) had an ITP exacerbation. Likewise, Lee et al. demonstrated that only 31% of ITP pts had platelet (PLT) count reduction with a 17% of ITP exacerbation. Moreover, Feng et al. recently demonstrated that, despite the PLT drop, an adequate PLT count response was obtained after the begin of a target therapy Aims: We conducted this retrospective study to evaluate the safety of mRNA vaccines and the impact of COVID disease in the real-life setting of ITP pts followed in our center. Methods: A cohort of 45 ITP pts was enrolled; we collected blood samples from March 2021 to November 2022, in a time variable between one and three weeks after the shots, according to clinical practice and patients’ clinical needs. All pts received 2 vaccine shots, 30 received a first booster and 10 a second one. Overall, 24 pts (53%) developed a CTCAE v5.0 G1-2 COVID infection; only 2 (4%) G3. At the time of the first 2 doses, 17 pts (38%) were under TPOra therapy, while 28 (62%) were just under observation. At the time of the third dose, 2 of these 17 pts have switched TPOra, and 6 pts had started a new TPOra therapy. Mentioning the vaccines used, most pts received the same type for the first three shots, or Comirnaty or Moderna; while all pts received Comirnaty Origin Omicron Ba.4-5 as second booster. Pts characteristics in Table1. Results: After the first dose, we observed a PLT decrease in 26 pts (58%), with a median drop of 29.000/mmc (1.000-252.000). After the second shot, 23 (53%) pts experienced a drop with a median decline of 28.000/mmc (2.000-249.000). The third dose caused a PLT drop in 13 pts (43%), with a median of 31.000/mmc (9.000-106.000). After the II booster only two (20%) pts developed a mild medium drop of 6.000 PLT/mmc. About the corticosteroid-based rescue therapy, we administered it only for PLT counts <30.000/mmc. After the first shot 1 pts (2%) received it, and 4 (8%) after the second one. Moreover, 1 pts (2%) needed a rescue therapy with intravenous immunoglobulin after both I and II doses. However, no pts needed it after the I or II booster. We did not observe a statistical difference in the median PLT decrease between pts who were receiving an active treatment and those who were only on observation after the first, the second dose, the first booster; respectively (p=0.7, p=0.4, p=0.9). Among the 24 pts who developed a G1-2 COVID infection, 2 received therapy with nirmatrelvir/ritonavir. Both patients who developed a G3 infection received an active therapy, one with sotrovimab and one with nirmatrelvir/ritonavir. Overall, between the 26 COVID-infected pts, 9(35%) experienced a median PLT drop of 37.000/mmc(3.000-90.000). One of these needed a steroid-based rescue therapy and one increased his TPOra dosage, while the others maintained the same therapy. Summary/Conclusion: Despite the apparent decline of COVID infection and the efficacy of vaccines, our ITP pts still need an eye on the impact of PLT count reduction on their safety and quality of life. In our study we observed a PLT decrease in about 50% of pts, but it was significant in only few of these. Indeed, less than 15% of pts needed a rescue therapy, consistently with literature. These small cohort confirmed how the COVID vaccine remains a valid and safe weapon, to avoid worse consequences due to the viral infection.Keywords: Platelet count, Vaccination, Idiopathic thombocytopenic purpura (ITP), COVID-19